With the development of wireless communication technologies, various wireless communication systems are in practical use. Consequently, multimode wireless communication apparatuses (multimode wireless terminals) supporting these wireless communication systems are demanded.
Such terminals include a software wireless terminal that has a signal processor composed of a programmable device reconfigurable by rewriting software for such as an FPGA (field programmable gate array) or reconfigurable processor and supports each wireless communication system by reconfiguring the signal processor. Refer to J. Mitola, “The Software Radio Architecture” IEEE Communications Magazine, 1995, Vol. 33, No. 5, pp. 26-38, for example.
The software wireless terminal with the programmable device is fed configuration data including a circuit configuration, to reconfigure the signal processor every time wireless communication systems are switched. Consequently, the software wireless terminal, with a high frequency of switching wireless communication systems, requires a long time for reconfiguration, thus decreases its communication efficiency.
Another type of software wireless terminal is known that has a different function processor for implementing different functions depending on a wireless communication system and a common function processor for implementing common functions common to each wireless communication system, and supports each wireless communication system by implementing specific functions of the different function processor and common functions of the common function processor. Refer to Japanese Patent Unexamined Publication No. H11-346383, for example.
The software wireless terminal having the different function processor and common function processor is fed a parameter (difference information) corresponding to a wireless communication system to specify the functions, and thus wireless communication systems can be switched faster than the case where a signal processor is reconfigured. However, the software wireless terminal, including a redundant general-purpose circuit supporting plural wireless communication systems, consumes more power than that including a circuit supporting a single wireless communication system.
To sum up, manners of switching wireless communication systems in a software wireless terminal include reconfiguring the signal processor and specifying the functions by parameter input. With a low frequency of switching wireless communication systems, reconfiguring the signal processor has an advantage in power consumption. With a high frequency, specifying the functions by parameter input has an advantage in communication efficiency.
However, in a conventional software wireless terminal, its manner of switching wireless communication systems is fixed. Although an optimum manner of switching wireless communication systems is different depending on an operation environment, a conventional software wireless terminal has difficulty in switching wireless communication systems according to an operation environment.